Hysterectomy & Pelvic Floor Disorders
According to several studies, hysterectomy is a risk factor for pelvic organ prolapse[24–27] and urinary incontinence.[4,27–31] The procedure has also been associated with bowel dysfunction,[32,33] pelvic organ fistula disease and sexual dysfunction. Pelvic floor dysfunction generates substantial morbidity among elderly women, results in important costs for healthcare systems worldwide[36–38] and affects most domains of individual quality of life and daily function.[39,40] In cases of severe dysfunction, corrective surgery is often the treatment of choice, and in the USA for example, more than 300,000 procedures for pelvic organ prolapse are performed annually. The population-based prevalence of urinary incontinence ranges from 25 to 49% depending on definition and population.[40,43,44] Urinary incontinence is, according to several studies, one of the most common reasons for the elderly to be institutionalized.[45,46] Bowel dysfunction and constipation are also common problems affecting between 2 and 27% of the female population in developed countries. It has been suggested, but not well investigated, that women having a hysterectomy differ from other women in healthcare-seeking behavior, which may influence the incidence of pelvic floor disorders subsequent to hysterectomy. This was considered in a study where varicose vein stripping and hallux valgus surgery were used as indicators of propensity for elective surgery. Hysterectomy only showed a negligible association with risks for hallux valgus surgery and varicose vein stripping.
There are several possible mechanisms for the development of pelvic floor dysfunction subsequent to hysterectomy. It has traditionally been postulated that hysterectomy disrupts local nerve supply and distorts pelvic anatomy, which adversely affect pelvic organ function. Direct iatrogenic injury to the soft tissue supportive structures and disruption of the supporting fascia and ligaments are actions that may also distort pelvic organ anatomy subsequent to a hysterectomy. Changes to anatomical relationships between the bowel, bladder and vagina after surgery may have a direct impact on the function of these organs. Alterations of pelvic organ function could also be attributed to changes in functional dynamic anatomy and innervations of pelvic organs.[48,49] Furthermore, a decreased collateral blood supply to the pelvic organs and their surrounding tissues may have a long-term impact on pelvic organ function.
Disruption of the Supporting Fascia & Ligaments
DeLancey has described three levels of normal vaginal support and, depending on the degree of disruption to the supporting fascia and ligaments, various types of prolapse may occur after hysterectomy. The first level of support (level I) is represented by vertical fibers of the paracolpium, which are a continuation of the cardinal ligaments. Insufficient suspension of the vaginal apex by these ligaments can lead to vaginal vault prolapse after surgery. Disruption of level II vaginal support (pubocervical or rectovaginal fascia) may result in the development of anterior vaginal wall prolapse (cystocele) or posterior vaginal wall prolapse (recto-, entero-, sigmoido- or perito-neocele). Cadaver studies have shown that it is not possible to evert the vaginal apex as long as these fascias are intact. In level III, the attachments of the distal vagina to the medial margins of the levator ani muscles are very dense to ensure that the lower portion of the vaginal wall remains attached in this region.
Risk of Nerve Damage During Hysterectomy
The bilateral inferior hypogastric plexa provide sympathetic and parasympathetic innervation to the lower pelvic viscera and are located in close proximity to the proximal vagina and distal rectum. During the course of hysterectomy, the pelvic plexus may be at risk of injury in several areas: at the division of the cardinal ligaments; at the blunt dissection of the bladder from the uterus; at the dissection of the paravaginal tissue; and at the removal of the cervix. The pelvic floor muscles, as well as urethral and anal sphincters, are also innervated by distal branches of the pudendal nerves, supplying motor and sensory innervations.
Damage to the distal branches of the pudendal nerves and the inferior hypogastric plexa may impede the intricate urethral sphincter closing mechanism and cause chronic or progressive denervation injury. This may eventually lead to the development of incontinence.[28,49] Posthysterectomy alterations in urethral innervation and anatomy may also give rise to changes in urethral pressure dynamics and bladder neck support, resulting in deterioration of urethral function. However, stress urinary incontinence and urge urinary incontinence may have different pathophysiologies, as well as different predisposing risk factors.
The pathophysiological basis for bowel dysfunction after hysterectomy may involve changes in rectal support and dynamics. The pelvic plexus is of paramount importance in the coordinated contractions of the smooth muscle of the bowel, and nerve conductance impairment may result in bowel dysfunction and constipation. Sharp or blunt severing of pelvic organ supportive tissues at the time of hysterectomy may interfere with the anorectal innervation, mainly the pudendal nerve, and provide the pathophysiologic basis for anal incontinence.
Iatrogenic Injury During Surgery
Iatrogenic injury to the urinary tract and bowels occasionally occurs during hysterectomy.[55,56] The incidence of urinary tract injury, detected by cystoscopy, was reported to be as high as 4.3% in a study by Ibeanu et al.. The formation of fistulas between pelvic organs subsequent to hysterectomy is thought, among other factors, to be a complication of iatrogenic injury to the organs involved. Possible mechanisms behind fistula formation in the aftermath of hysterectomy include injury during the dissection of the bladder, sutures incorporated into the bladder and direct injury to the lower urinary tract or to the bowels,[58,59] most commonly the rectum. Without the dense smooth muscle uterus in place to act as a protective buffer, postoperative infections of the vagina or paravaginal tissues may act as a source for fistula formation soon after surgery, a process that may be precipitated by injury to the surrounding pelvic organs.
Aging Health. 2013;9(2):179-187. © 2013 Future Medicine Ltd.